The four-year NTSB investigation ended with the adoption of its final report on August 23, 2000. The report's conclusion was that the probable cause of the accident was an explosion of flammable fuel/air vapors in a fuel tank, and, although it could not be determined with certainty, the most likely cause of the explosion was a short circuit.[8] As a result of the crash, new requirements were developed for aircraft to prevent future fuel tank explosions.[9]